Stabilization of viscous petroleum oils



Patented Apr. 14, 1942 STABILIZATION OFOYIISCOUS PETROLEUM Melvin A. Dietrich, Claymont, DeL, asslgnor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application May 15, 1940,

Serial No. 335,371

, 13 Claims.

This invention relates to the stabilization of viscous'petroleuzn oils-and particularly to inhibiting deterioration in color of such oils caused by the action of oxygen, heator metals and the like. Color and color stability-are frequently employed by consumers as measures of the qualtiy of the oil particularly as set forth in various specifications. Accordingly, the problem of providing products of suitable and stable color becomes of considerable importance to the refiner. It is well known that petroleum products and particularly the viscous petroleum oils tend to deteriorate and become darker in color through oxidation. Such deterioration frequently occurs during long periods of storage of the oils under oxidizing conditions. The degree of darkening in color is increased by an increase in temperature and also by the presence of some metals and particularly iron.

Many compounds have been suggested for the stabilization of petroleum oils. of such compounds, while efiective in inhibiting oxidation, tend to become dark colored themselves and thus impart objectionable color to the oil. Other compounds proposed heretofore have only limited solubility in the oils and hence tend to separate from the oils during storage, especially at low temperatures, or require the use of solvents or blending agents to maintain them in solution in the oils.

It is an object of the present invention to provide a method for stab! the color oi viscous petroleum oils. Another oblect is to provide new compounds for stabilizing the color cl viscous petroleum oils, which compounds are readily soluble in the oils and do not themselves deteriorate to form colored products in the oils. A iurther object is to provide compounds which are eil'ec tive for stabilizing the color oi viscous petroleum oils particularly at elevated temperatures and in the presence of metals such as iron. it. still further object is to provide stable solutions of certain new compounds in oils which new compounds are effective to stabilize the color of the oils. Other objects are to provide new-compositions of matter and to advance the art. Still other objects will appear hereinafter.

The above and other objects may be accomplished in accordance with my invention which comprises incorporating in viscous petroleum oils, which are normally subject to deterioration in color, a small proportion of a condensation product of 1 mole of an aliphatic polyamine, in which two amino groups are primary amino groups directly attached to dificrent aliphatic carbon atoms, with from. 3 to moles of an aliphatic aldehyde of at least 3 carbon atoms having at least one replaceable hydrogen atom on the carbon adjacent to the =CHO group. I have found that such condensation products,

which are readily soluble in the viscous petroleum oils, will inhibit deterioration in color of the oils, even at temperatures above atmospheric temperatures, and in the presence of metals such as iron. The condensation products do not deteriorate themselves to form colored products and hence the color of their solutions in the viscous petroleum oils will not change to any material extent over long periods of time.

The polyamine may be any aliphatic amine having two primary amino groups directly attached to different aliphatic carbon atoms. The polyamines may contain substituents such as nitrogen, oxygen and sulfur as in amino, hydroxy, ether and thioether groups. They may contain aromatic orother cyclic groups. The term aliphatic" polyamine as employed herein and in the claims will be understood to include such substituted, as well as unsubstituted, compounds. Preferably, however, the polyamines will consist of the elements carbon, hydrogen and nitrogen and particularly should be polyaminoalkanes. By the term polyaminoalkanes, I mean that they consist of carbon, hydrogen and nitrogen and do not contain aromatic or other cyclic groups. One important sub-group of the class of polyamines is the diaminoalkanes of which diaminoethane is an example. By the term primary amino group, I mean the radical The aldehyde may be any aliphatic aldehyde of 3 or more carbon-atoms and which contains a hydrogen atom on the carbon adjacent to the -CH0 group. They may contain amino, nitro, hydroiry, ether, aromatic or other cyclic groups. Such substituents, when present, should preferably be attached to carbon atoms other than the carbon atom adjacent to the -CH0 group. The preferred aldehydes are those which, except for the oxygen of the -CH0 group, consist of carbon and hydrogen and particularly those which contain no aromatic or other cyclic group. The aldehydes, which, except for the oxygen of the -CHO group, consist of carbon and hydrogen and contain no aromatic or other cyclic group, will be hereinafter referred to as alkyl aidehydes.

By viscous petroleum oils, I mean oils derived from petroleum and intend to include fuel oils, oils used in heat transfer apparatus, electrical transformers and greases, as well as the usual lubricating oils, but intend to exclude the nonviscous oils such as gasoline and kerosene.

Theconcentration of condensation products to be added to oil will be determined largely by the degree of stabilization desired. The preferred tive methods of preparing representative compounds of my invention, the following examples are given, in which the parts are by. weight:

EXAMPLE 1 Thirty-two and four tenths (32.4) parts (0.45 mole) of butyraldehyde are dissolved in 144 parts of ether and placed in a reaction vessel equipped with two outlets and a mechanical stirrer. Twelve and nine-tenths (12.9) parts (0.15 mole) of a 70% aqueous solution of diaminoethane are dissolved in 40 parts of ethyl alcohol and dropped onto the aldehyde solution with stirring and cooling. The reaction mixture is allowed to stand hours, following which the solvent is removed by evaporation and the residue distilled. Thirty parts of a product boiling between 80 C. and 170 C./6 mm. are obtained which can be divided into two fractions as follows:

Nitrogen content Boiling range Fraction at 6 P: r vent 80-165 14. 03 165-170 I ll). 53

EXAMPLE 2 Forty-three and two-tenths (43.2) parts (0.6

mole) of butyraldehyde are dissolved in 72 parts of ether and placed in a reaction vessel as in Example 1. Twelve and nine-tenths (12.9)) parts (0.15 mole) of a 70% aqueous solution of diaminoethane are dissolved in 20 parts of absolute alcohol and dropped with stirring onto the aldehyde solution. After standing overnight, the 501- I vent is removed by evaporation on a. steam bath,

leaving parts of a pale yellow liquid which, on analysis, yielded 11.31% nitrogen.

EXAMPLE 3 Eighty-six and four-tenths (86.4) parts (1.2 moles) of freshly distilled butyraldehyde are placed in a reaction vessel as in Example 1, and 17.2 parts (0.2 mole) of a 70% aqueous solution of diaminoethane dropped in with agitation, the

' temperature of the reaction mixture being kept at 70-75 C. After 2 hours agitation, the reaction mixture is diluted withbenzene, the water layer separated, and the benzene layer dried with anhydrous sodium sulfate. After filtration and removal of solvent, 68 parts of a red liquid are obtained which has a nitrogen content of 9.90%.

EXAMPLE 4 EXAMPLE 5 Fifty-seven and six-tenths (57.6) parts (0.8 mole) of butyraldehyde are dropped onto 14.6 parts (0.1 mole) of triethylenetetramine with vigorous agitation. The reaction -mixture is stirred 12 hours and then allowed to stand 15 hours. It is then dissolved in benzene, washed with water, and dried over anhydrous sodium sulfate. After removal of the solvent, 49 parts of an orange-red liquid are obtained, having a nitrogen content of 10.56%.

The color stabilizing action of these products was determined on a naphthenic base S. A. E. 30 oil. The data, presented inthe following table, were obtained by heating 50 grams of oil in a 250 cc. pyrex beaker open to the air at 150 C. for six hours, and comparing the color of the oil before and after this treatment. Color measurements were determined in units of a scale of true color from which per cent inhibition of color formation could be calculated.

Table I Molar ratio Concen- Color 1 Summer gg ggfi tration inhibition Per cent by weight Per cent None 1 Example l-fraction l. 3 to l 0. l 81 Example ltracti0n 2. 3 to 1 0. l 75 Example 2 4 t0 1 0.1 81

In the following table, the color stabilizing action was determined by heating 20 grams of a naphthenic base S. A. E. 30 oil in a 50 cc. pyrex beaker open to the air at 150 C. for 6 hours. A piece of autobody steel /2 in. x /2 in.) was immersed in the oil during the heating period. Color changes were measured on a Duboscq colorimeter, using the unheated original oil as a standard. From these measurements, Color Inhibition was calculated.

Table II Molar ratio Stabilizer aldehyde w Ct oncen- C diamine ation hihition Percent by weigh! Percent 84 Example 5. 85

It will be noted that the preceding examples and tests are given for illustrative purposes only.

Many variations and modifications can be made in the relative proportions, the conditions of reaction and treatment and in the components of the condensation products. For example, suitable compounds within my invention may be prepared by condensation of 3 to 10 moles of any one or more of the aldehydes in the following list with 1 mole of any one or more of the polyamines in the following list:

'I-he condensation products from such aldehydes and polyamines may be prepared in the manner shown in the preceding examples, either with or without the use of a solvent, such as aldrogen.

cohol, benzene or petroleum hydrocarbons. Mixtures of aldehydes may be reacted with a polyamine or a mixture of polyamines to provide a highly effective product. Thus a mixture of 3 moles of butyraldehyde and 1 mole of Z-ethylhexanal may be interacted with 1 mole of 1,2- diaminopropane to produce a satisfactory stabilizer of high oil solubility. The nitrogen anbe used wherever petroleum lubricants are efiective. They may be added to the oil in the refining process in order to inhibit color deterioration during heating or distillation.- They may be employed in conjunction with other lubricant addition agents, such as phosphates, phosphites,

halogenated compounds, metallic soaps, pour point depressants, viscosity index improving agents, decarbonizers. gum solvents and the like. They may be employed in greases and in grease compositions of the usual types.

I claim:

1. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of an aliphatic polyamine in which two amino groups are primary amino groups directly attached to different aliphatic carbon atoms with from 3 to 10 moles of an aliphatic aldehyde of at least 3 carbon atoms having at least one hydrogen atom on the carbon adjacent to the ---CH0 group. I

2. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of an aliphatic polyamine consisting of carbon, hydrogen and nitrogen in which two amino groups are primary amino groups directly attached to diiierent aliphatic carbon atoms with from 3 to 8 moles of an alkyl aldehyde of at least 3 carbon atoms having at least one hydrogen atom on the carbon adjacent to the CH0 group.

3. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole 0! an aliphatic polyamine consisting of carbon, hydrogen and nitrogen in which two amino zroupsare primary amino groups directly attached to diflferent aliphatic carbon atoms with from 3 to 8 moles of an acyclic aldehyde of from 3 to 12 carbon atoms having. at least onehydrogen atom on the carbon adjacent to the ---CH0 group and which aldehyde, except for the oxygen of the --CH0 group, consists of carbon and hy- 4. A viscous petroleum oil normally subject to deterioration in color having incorporated therein mole of an, aliphatic polyamine consisting of carbon, hydrogen and nitrogen in which two amino groups are primary amino groups directly attached to difierent aliphatic carbon atoms with from 3 to 8 moles of butyraldehyde.

5. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of a diaminoalkane in which the two amino groups are primary amino groups attached to different carbon atoms with from 3 to 8 moles of an acyclic aldehyde of from 3 to 12 carbon atoms having at least one hydrogen atom on the carbon adjacent to the CH0 group and which'aldehyde, except for the oxygen of the ---CH0 group, consists of carbon and hydrogen.

6. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of a diaminoalkane in which the two amino groups are primary amino groups attached to difierent carbon atoms with 4 moles of butyraldehyde.

7. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of diaminoethane with from 3 to 8 moles of an aliphatic aldehyde of at least 3 carbon atoms having at least one hydrogen atom on the carbon adjacent thew-CHO group and which aldehyde, except for the oxygen of the CH0 group, consists of carbon and hydrogen.

8. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of diaminoethane with from 3 to 8 moles of butyraldehydes.

9. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of ;a condensation product of 1 mole of ethylenediamine with 4 moles of butyraldehyde.

10. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of triethylenetetramine with from 3 to 8 moles of an acyclic aldehyde of from 3 to 12 carbon atoms having at least one hydrogen atom on the carbon adjacent to the CH0 group and which aldehyde, except for the oxygen of the-CHO group, consists of carbon and hydrogen.

11. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of triethylenetetramine with from 3 to 8 moles of butyraldehyde.

12. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of the condensation prodnot of 1 mole of triethylenetetramine with 8 moles of butryaldehyde.

- 13. A viscous petroleum oil normally subject to deterioration in color having incorporated therein a small proportion of a condensation product of 1 mole of 1,2-diaminopropane with from 3 to 8 moles of butyraldehyde.

MELVIN A. DIETRICH.

' CERTI F ICATE OF CORRECTI ON. Patent No. 2,279,561. I April 11;, 1914.2.

MELVIN A DI ETRICH Y It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, first column, line 6, for "qualtiy" read qualitypage 5', second column, line 14.1 claim 9, for "ethylenediax nine" read, -fdiaminoethene-- and thet the sag-id,

Letters Patent should 'be read with this correction therein thatthe same meya confozm to the record of the case in the Patent Office.

Signed ani sealed this 16th day of June, A. D.'19L;2.

Henry Van 'Arsdale (seal) Acting Commissioner f Patents CERTIFICATE OF CORRECTION. Patent No. 2,279,561. April 1h, 191m.

HELVINA. DIETRICH.

It is hereby certified that error appears in the printed specifiehtion of the above numbered patent requiring correction as follows: Page 1, first column, line 6, for "qualtiy" read "qualitypage 3', second columni, line 141 claim 9, for "ethylenediainine" read 'd 1 1noethe ,ne--; and the: the a -id Letters Patent should 'be read with this correction therein that-the same melyconfonn to the record the case in the Patent Office.

Signed and sealed this law day of June, A. D. 191 2.

Henry Van Ar adale (Seal) Acting Commissioner f Patent 

